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Neutron capture cross sections of light neutron-rich nuclei relevant for $$r$$-process nucleosynthesis

Bhattacharyya, A.*; Datta, U.*; Rahaman, A.*; Chakraborty, S.*; Aumann, T.*; Beceiro-Novo, S.*; Boretzky, K.*; Caesar, C.*; Carlson, B. V.*; Catford, W. N.*; et al.

Physical Review C, 104(4), p.045801_1 - 045801_14, 2021/10

 被引用回数:0 パーセンタイル:0.02(Physics, Nuclear)



Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes; Coulomb excitation of $$^{182}$$Hg, $$^{184}$$Hg, $$^{186}$$Hg and $$^{188}$$Hg

Wrzosek-Lipska, K.*; Rezynkina, K.*; Bree, N.*; Zieli$'n$ska, M.*; Gaffney, L. P.*; Petts, A.*; Andreyev, A. N.; Bastin, B.*; Bender, M.*; Blazhev, A.*; et al.

European Physical Journal A, 55(8), p.130_1 - 130_23, 2019/08

 被引用回数:9 パーセンタイル:80.1(Physics, Nuclear)

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass $$^{182-188}$$Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0$$^{+}_{1,2}$$, 2$$^{+}_{1,2}$$, and 4$$^{+}_{1}$$ states was observed in all nuclei under study. Reduced $$E2$$ matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.


Fusion reaction $$^{48}$$Ca+$$^{249}$$Bk leading to formation of the element Ts (Z=117)

Khuyagbaatar, J.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; 浅井 雅人; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review C, 99(5), p.054306_1 - 054306_16, 2019/05


 被引用回数:14 パーセンタイル:89.48(Physics, Nuclear)



Population of nuclides with Z$$ge$$98 in multi-nucleon transfer reactions of $$^{48}$$Ca+$$^{248}$$Cm

Devaraja, H. M.*; Heinz, S.*; Beliuskina, O.*; Hofmann, S.*; Hornung, C.*; M$"u$nzenberg, G.*; Ackermann, D.*; Gupta, M.*; Gambhir, Y. K.*; Henderson, R. A.*; et al.

European Physical Journal A, 55(2), p.25_1 - 25_9, 2019/02

 被引用回数:8 パーセンタイル:72.63(Physics, Nuclear)

The results for nuclei above curium, produced in multi-nucleon transfer reactions of $$^{48}$$Ca+$$^{248}$$Cm at the velocity filter SHIP of GSI Darmstadt, are presented. Spontaneous fission and $$alpha$$ activities have been used to study the population of nuclei with lifetimes ranging from few milliseconds to several days. We observed several, relatively neutron-rich isotopes with atomic numbers Z $$ge$$ 98; among them a weak 224 millisecond activity which we tentatively attributed to $$^{260}$$No. The measured cross-sections of the observed nuclei give hope that multi-nucleon transfer reactions are a way to reach new neutron-rich heavy and superheavy nuclei, which are not accessible in other reactions. We compare our results with data from earlier experiments and discuss limitations and future perspectives of the method.


Ground-state configuration of neutron-rich $$^{35}$$Al via Coulomb breakup

Chakraborty, S.*; Datta, U.*; Aumann, T.*; Beceiro-Novo, S.*; Boretzky, K.*; Caesar, C.*; Carlson, B. V.*; Catford, W. N.*; Chartier, M.*; Cortina-Gil, D.*; et al.

Physical Review C, 96(3), p.034301_1 - 034301_9, 2017/09

 被引用回数:2 パーセンタイル:23.28(Physics, Nuclear)



Beta-delayed proton emission from $$^{20}$$Mg

Lund, M. V.*; Andreyev, A. N.; Borge, M. J. G.*; Cederk$"a$ll, J.*; De Witte, H.*; Fraile, L. M.*; Fynbo, H. O. U.*; Greenlees, P. T.*; Harkness-Brennan, L. J.*; Howard, A. M.*; et al.

European Physical Journal A, 52(10), p.304_1 - 304_14, 2016/10

 被引用回数:13 パーセンタイル:73.2(Physics, Nuclear)

Beta-delayed proton emission from $$^{20}$$Mg has been measured at ISOLDE, CERN, with the ISOLDE Decay Station setup including both charged-particle and $$gamma$$-ray detection capabilities. A total of 27 delayed proton branches were measured including seven so far unobserved. An updated decay scheme, including three new resonances above the proton separation energy in $$^{20}$$Na and more precise resonance energies, is presented. Beta-decay feeding to two resonances above the Isobaric Analogue State in $$^{20}$$Na is observed. This may allow studies of the 4032.9(2.4) keV resonance in $$^{19}$$Ne through the beta decay of $$^{20}$$Mg, which is important for the astrophysically relevant reaction $$^{15}$$O($$alpha$$,$$gamma$$)$$^{19}$$Ne. Beta-delayed protons were used to obtain a more precise value for the half-life of $$^{20}$$Mg, 91.4(1.0) ms.


Recoil-$$alpha$$-fission and recoil-$$alpha$$-$$alpha$$-fission events observed in the reaction $$^{48}$$Ca + $$^{243}$$Am

Forsberg, U.*; Rudolph, D.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Fahlander, C.*; Gates, J. M.*; Golubev, P.*; Gregorich, K. E.*; Gross, C. J.*; et al.

Nuclear Physics A, 953, p.117 - 138, 2016/09

 被引用回数:33 パーセンタイル:92.7(Physics, Nuclear)

$$^{48}$$Ca + $$^{243}$$Am反応による115番元素合成実験で観測された$$alpha$$崩壊連鎖について、最近我々が報告したドイツGSIで測定したデータと過去に報告されたロシアDubna及び米国LBNLで測定されたデータのすべてを使い、その起源を調査した。それらのデータの中に、反跳核-$$alpha$$-($$alpha$$)-核分裂タイプの短い崩壊連鎖が14事象観測されており、そのうちのいくつかは中性子が2個放出されてできる$$^{289}$$Mc起源であるとこれまで解釈されてきた。一方、今回我々は、これらの短い崩壊連鎖のほとんどが、中性子が3個放出されてできる$$^{288}$$Mc起源であり、崩壊連鎖の途中でEC崩壊して核分裂したものであろうと再同定した。


Review of even element super-heavy nuclei and search for element 120

Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; M$"u$nzenberg, G.*; Antalic, S.*; Barth, W.*; Burkhard, K. G.*; Dahl, L.*; Eberhardt, K.*; et al.

European Physical Journal A, 52(6), p.180_1 - 180_34, 2016/06

 被引用回数:122 パーセンタイル:92.05(Physics, Nuclear)

The reaction $$^{54}$$Cr+$$^{248}$$Cm was investigated at the velocity filter SHIP at GSI with the intention to study production and decay properties of isotopes of element 120. Three correlated signals were measured, which occurred within a period of 279 ms. The heights of the signals correspond with the expectations for a decay sequence starting with an isotope of element 120. However, a complete decay chain cannot be established, since a signal from the implantation of the evaporation residue cannot be identified unambiguously. Measured properties of the event chain are discussed in detail. The result is compared with theoretical predictions. Previously measured decay properties of even element super-heavy nuclei were compiled in order to find arguments for an assignment from the systematics of experimental data. In the course of this review, a few tentatively assigned data could be corrected. New interpretations are given for results which could not be assigned definitely in previous studies. The discussion revealed that the cross-section for production of element 120 could be high enough so that a successful experiment seems possible with presently available techniques. However, a continuation of the experiment at SHIP for a necessary confirmation of the results obtained in a relatively short irradiation of five weeks is not possible at GSI presently. In the summary and outlook section we also present concepts for the continuation of research in the field of super-heavy nuclei.


Remarks on the fission barriers of super-heavy nuclei

Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; M$"u$nzenberg, G.*; Antalic, S.*; Barth, W.*; Dahl, L.*; Eberhardt, K.*; Grzywacz, R.*; et al.

European Physical Journal A, 52(4), p.116_1 - 116_12, 2016/04

 被引用回数:25 パーセンタイル:88.29(Physics, Nuclear)

Shell-correction energies of super-heavy nuclei are approximated by using Q$$_{alpha}$$ values of measured decay chains. Five decay chains were analyzed, which start at the isotopes $$^{285}$$Fl, $$^{294}$$118, $$^{291}$$Lv, $$^{292}$$Lv and $$^{293}$$Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far.


Observation of new neutron-deficient isotopes with Z$$ge$$92 in multinucleon transfer reactions

Devaraja, H. M.*; Heinz, S.*; Beliuskina, O.*; Comas, V. F.*; Hofmann, S.*; Hornung, C.*; M$"u$nzenberg, G.*; 西尾 勝久; Ackermann, D.*; Gambhir, Y. K.*; et al.

Physics Letters B, 748, p.199 - 203, 2015/09


 被引用回数:53 パーセンタイル:96.62(Astronomy & Astrophysics)

In deep inelastic multinucleon transfer reactions of $$^{48}$$Ca +$$^{248}$$Cm we observed about 100 residual nuclei with proton numbers between Z =82 and Z =100. Among them, there are five new neutron-deficient isotopes: $$^{216}$$U, $$^{219}$$Np, $$^{223}$$Am, $$^{229}$$Am and $$^{233}$$Bk. As separator for the transfer products we used the velocity filter SHIP of GSI while the isotope identification was performed via the $$alpha$$-decay chains of the nuclei. These first results reveal that multinucleon transfer reactions together with here applied fast and sensitive separation and detection techniques are promising for the synthesis of new isotopes in the region of heaviest nuclei.


Identification of deformed intruder states in semi-magic $$^{70}$$Ni

Chiara, C. J.*; Weisshaar, D.*; Janssens, R. V. F.*; 角田 佑介*; 大塚 孝治*; Harker, J. L.*; Walters, W. B.*; Recchia, F.*; Albers, M.*; Alcorta, M.*; et al.

Physical Review C, 91(4), p.044309_1 - 044309_10, 2015/04

 被引用回数:33 パーセンタイル:91.67(Physics, Nuclear)

アルゴンヌ国立研究所にて中性子過剰核$$^{70}$$Niを$$^{70}$$Znの多核子移行反応によって生成し、$$gamma$$線検出器GRETINAを用いて$$gamma$$線分光を行った。その結果、$$2^+_2$$, $$4^+_2$$準位を初めて観測した。これらの準位は小さな模型空間を採用した殻模型計算では再現されないため、陽子の$$f_{7/2}$$軌道からの励起を伴った大きな変形状態であると考えられる。本論文の理論グループが2014年に発表した大規模殻模型計算によって$$^{70}$$Niの励起状態を解析した結果、これらの状態は大きなプロレート変形を持つ状態とよく対応することがわかった。この結果は、中性子過剰ニッケル同位体における変形共存が$$^{68}$$Ni以外にも存在することを実証するとともに、中性子過剰核における大規模殻模型計算の予言能力を確かめるものである。


Selected spectroscopic results on element 115 decay chains

Rudolph, D.*; Forsberg, U.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1185 - 1190, 2015/02

 被引用回数:6 パーセンタイル:51.48(Chemistry, Analytical)



$$^{48}$$Ca + $$^{249}$$Bk fusion reaction leading to element Z = 117; Long-lived $$alpha$$-decaying $$^{270}$$Db and discovery of $$^{266}$$Lr

Khuyagbaatar, J.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; 浅井 雅人; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review Letters, 112(17), p.172501_1 - 172501_5, 2014/05

 被引用回数:182 パーセンタイル:98.56(Physics, Multidisciplinary)

ドイツ重イオン研究所のガス充填型反跳核分離装置TASCAを用いて$$^{48}$$Ca + $$^{249}$$Bk核融合反応で生成する原子番号117の超重元素の観測に成功した。この結果は、過去にロシアのフレーロフ研究所が報告した117番新元素の結果を再確認するもので、117番元素の合成及び発見を確かなものとする成果である。一方、117番元素からの$$alpha$$崩壊連鎖の最後の原子核は、過去に報告された$$^{270}$$Dbではなく、未知核種$$^{266}$$Lrであり、$$^{270}$$Dbは非常に長い寿命を持つ$$alpha$$崩壊核種であることを明らかにした。


Spectroscopic tools applied to element Z = 115 decay chains

Forsberg, U.*; Rudolph, D.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

EPJ Web of Conferences, 66, p.02036_1 - 02036_4, 2014/03

 被引用回数:5 パーセンタイル:84.63



Alpha-photon coincidence spectroscopy along element 115 decay chains

Rudolph, D.*; Forsberg, U.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

Acta Physica Polonica B, 45(2), p.263 - 272, 2014/02

 被引用回数:19 パーセンタイル:74.98(Physics, Multidisciplinary)



Superheavy element flerovium (element 114) is a volatile metal

Yakushev, A.*; Gates, J. M.*; T$"u$rler, A.*; Sch$"a$del, M.; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Block, M.*; Br$"u$chle, W.*; Dvorak, J.*; et al.

Inorganic Chemistry, 53(3), p.1624 - 1629, 2014/02

 被引用回数:84 パーセンタイル:98.58(Chemistry, Inorganic & Nuclear)

金表面に対する114番元素フレロビウム(Fl)の吸着挙動に関するガスクロマトグラフ研究について報告する。実験対象としたFlは$$^{244}$$Pu($$^{48}$$Ca, 3-4n)$$^{288,289}$$Fl反応で合成し、反跳核分離装置を利用して$$^{48}$$Caビームから単離した。Fl及びその$$alpha$$壊変核種である112番元素コペルニシウム(Cn)、そしてその周期表上の同族である14族(Pb)及び12族(Hg)、並びに不活性ガスであるRnの吸着挙動を、等温クロマトグラフィー及び熱クロマトグラフィーを利用した実験装置で観測した。その結果、2個のFl原子が測定され、PbやHgとは異なり直ちに吸着することはなかったが、室温の金表面に吸着した。得られたFlの吸着挙動は、最も近い同族元素であるPbと比較してより不活性であると言えるが、金表面でのFlの吸着エンタルピーの下限値は、金とFlが金属-金属結合を形成することを示している。したがって、Flは同族元素中で最も反応性が低い元素であると言えるが、その性質は金属である。


Spectroscopy of element 115 decay chains

Rudolph, D.*; Forsberg, U.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L. L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

Physical Review Letters, 111(11), p.112502_1 - 112502_5, 2013/09

 被引用回数:113 パーセンタイル:96.46(Physics, Multidisciplinary)

A high-resolution X-ray and $$alpha$$-ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum f$"u$r Schwerionenforschung. Thirty correlated decay chains were detected following the fusion-evaporation reaction $$^{48}$$Ca + $$^{243}$$Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z = 115. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z $$>$$ 112. Comprehensive Monte-Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation.


First prompt in-beam $$gamma$$-ray spectroscopy of a superheavy element; The $$^{256}$$Rf

Rubert, J.*; Dorvaux, O.*; Gall, B. J. P.*; Greenlees, P. T.*; Asfari, Z.*; Piot, J.*; Andersson, L. L.*; 浅井 雅人; Cox, D. M.*; Dechery, F.*; et al.

Journal of Physics; Conference Series, 420, p.012010_1 - 012010_10, 2013/03

 被引用回数:0 パーセンタイル:0.04

初めての超重元素即発インビーム$$gamma$$線分光実験を$$^{256}$$Rfを対象に行った。MIVOC法を用いた大強度$$^{50}$$Tiビームの開発を行い、実験を成功させた。$$^{256}$$Rfの回転励起状態をスピン20 $$hbar$$まで観測し、その慣性能率を導出した。これらのデータから、陽子数104には大きな変形閉殻が存在しないことが明らかとなった。


Determining the $$^{239}$$Np($$n$$,$$f$$) cross section using the surrogate ratio method

Czeszumska, A.*; Angell, C.; Burke, J. T.*; Scielzo, N. D.*; Norman, E. B.*; Austin, R. A. E.*; Boutoux, G.*; Casperson, R. J.*; Chodash, P.*; Hughes, R. O.*; et al.

Physical Review C, 87(3), p.034613_1 - 034613_6, 2013/03


 被引用回数:12 パーセンタイル:65.2(Physics, Nuclear)

Neutron-induced fission cross section data are needed in various fields of applied and basic nuclear science. However, cross sections of short-lived nuclei are difficult to measure directly due to experimental constraints. The first experimental determination of the neutron-induced fission cross section of $$^{239}$$Np at non-thermal energies was performed. The Surrogate Ratio Method (SRM) was employed to indirectly deduce the $$^{239}$$Np($$n$$,$$f$$) cross section. The surrogate reactions used were $$^{236}$$U$$(rm ^3He,p)$$ and $$^{238}$$U$$(rm ^3He,p)$$ with the reference cross section given by the well-known $$^{239}$$Np($$n$$,$$f$$) cross section. The ratio of observed fission reactions resulting from the two formed compound nuclei, $$^{238}$$Np and $$^{240}$$Np, was multiplied by the directly-measured $$^{237}$$Np($$n$$,$$f$$) cross section to determine the$$^{239}$$Np($$n$$,$$f$$) cross section. The $$^{239}$$Np($$n$$,$$f$$) cross section was determined with an uncertainty ranging between 3 - 30% over the energy range of 0.2 - 20 MeV.


$$beta$$-delayed fission of $$^{186,188}$$Bi isotopes

Lane, J. F. W.*; Andreyev, A. N.*; Antalic, S.*; Ackermann, D.*; Gerl, J.*; He${ss}$berger, F. P.*; Hofmann, S.*; Huyse, M.*; Kettunen, H.*; Kleinb$"o$hl, A.*; et al.

Physical Review C, 87(1), p.014318_1 - 014318_7, 2013/01

 被引用回数:14 パーセンタイル:69.2(Physics, Nuclear)

By using the technique of correlating implanted evaporation residues and their subsequent fission decay, $$beta$$-delayed fission ($$beta$$DF) of $$^{186}$$Bi has been identified for the first time and $$beta$$DF of $$^{188}$$Bi has been unambiguously confirmed. The experiments were performed at the velocity filter SHIP (GSI, Darmstadt). The $$beta$$DF probabilities for both nuclides were qualitatively estimated, and, in particular indications for a large value in the case of $$^{186}$$Bi are regarded.

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